I'm sort of addicted to Tchaikovsky at the moment. What with the Nutcracker, the first piano concerto, and Eugene Onegin all on the playlist at the moment. I'm off to see an all Tchaikovsky concert in Middlesbrough on the first.
As far as the violin concerto goes, I think I prefer Campoli / Argenta to Heifetz / Reiner. They are both excellent though, and I also like the Viktoria Mullova recording on Phillips.
The Heifetz Brahms is quite bracing and refreshing compared to the (infamously slow but still lovely) Nigel Kennedy that I have on LP. I need to find a knockout version of the Beethoven concerto, which up in till now has failed to engage me in the way that his piano concertos do. I did rather enjoy it live, though.

